WASHINGTON (Reuters) - Prime Minister Shinzo Abe on Wednesday expressed “deep repentance” over Japan’s role in World War Two, even as he declared Tokyo’s emergence as a global security player in the face of China’s rising power in Asia.

Using the high-profile platform of a landmark speech to the U.S. Congress, Abe insisted that Japan must not avert its eyes from the suffering of Asian peoples from its wartime behavior but he stopped short of issuing his own apology, instead upholding statements by his predecessors.

With Abe’s comments on Japan’s war record unlikely to satisfy critics who had demanded he go further, the conservative premier chose to focus more on the future of the U.S.-Japan military alliance and press skeptical lawmakers to back a long-delayed Pacific free-trade pact.

“We now hold high a new banner that is a ‘proactive contribution to peace based on the principle of international cooperation,’” Abe said a day after he and President Barack Obama cemented new guidelines for Japan’s military to support U.S. forces beyond its waters. He has proposed changes to Japan's pacifist post-war constitution to make this possible.

Receiving a warm welcome from lawmakers reflecting Japan’s status as America’s staunchest Asian ally, Abe, the first Japanese prime minister to address a joint meeting of Congress, used his speech to send a stern message to China, which is locked in maritime disputes with Japan and other Asian neighbors.

Referring to the “state of Asian waters,” Abe called for adherence to principles of peaceful negotiation, saying countries must not “use force or coercion to drive their claims.”

Abe's speech to Congress was a moment deeply symbolic of the reconciliation between former World Two enemies who are now the closest of allies. He spoke in slow, deliberate English and was interrupted frequently by applause and standing ovations.

Abe gave his address from the spot where President Franklin Roosevelt asked for a declaration of war against Imperial Japan after the 1941 bombing of Pearl Harbor in Hawaii. The speech also coincided with Japan’s national holiday marking the birthday of its wartime emperor, Hirohito.

Abe, who has sought to cast Japan’s aggressive World War Two-era conduct with a less apologetic tone, was under close scrutiny for how he chose to handle history in his speech.

The issue remains a sensitive one for Asian neighbors, especially China and U.S. ally South Korea, nearly 70 years after Japan’s defeat.

CRITICS WANTED NEW APOLOGY

Some American critics, including politicians and war veterans, had urged Abe to use the speech to make a strong public expression of contrition about World War Two to erase concerns that he is trying to dilute past official statements of remorse by Japanese leaders.

Abe did in fact offer new twist to his previous remarks when he spoke of his deeply symbolic visit to Washington’s World War Two memorial earlier on Wednesday, saying: “With deep repentance in my heart, I stood there in silent prayers for some time.”

But he stuck mostly to his past rhetoric, expressing “deep remorse” for Japan’s wartime conduct and saying he upheld previous Japanese apologies, including a 1995 landmark statement by then-premier Tomiichi Murayama.

"Our actions brought suffering to the peoples in Asian countries," he said. "We must not avert our eyes from that."

Abe made no mention of “comfort women,” the Japanese euphemism for the thousands of Korean and other Asian women forced into prostitution at Japanese military brothels before and during World War Two.

But he made an oblique reference to the controversial issue, saying “armed conflicts have always made women suffer the most.”

Abe also faced the formidable challenge of selling lawmakers on the Trans-Pacific Partnership (TPP) as U.S. and Japanese negotiators struggle to finalize terms of a bilateral deal essential to a broader 12-nation pact that would cover one-third of global trade.

Differences remained between Washington and Tokyo over automobiles and agriculture, which dashed hopes for a breakthrough announcement during Abe's official visit.

"The goal is near," Abe said. "Let us bring the TPP to a successful conclusion through our joint leadership."

Obama hopes Abe’s visit will help him build momentum on his trade agenda, including legislation to give him fast-track authority to speed any Pacific deal through Congress. But many of Obama’s fellow Democrats are reluctant to back him for fear it will hurt U.S. jobs.

Constrained by its pacifist constitution, Japan was criticized in the United States for decades for free-riding on U.S. military spending.

In the most dramatic shift in security policy since Japan's military was rebuilt after World War Two, Abe's cabinet last July adopted a resolution reinterpreting the constitution to allow Japan's armed forces to provide military aid to the United States and other friendly countries under attack.

Abe said security reform legislation would be enacted by this summer.

Japan's military is already considering joining the United States in maritime air patrols in the tense South China Sea in response to China's increasingly assertive pursuit of territorial claims, Japanese and U.S. sources familiar with the discussions told Reuters.

Abe has been under pressure to allay concerns that he seeks to whitewash Japan's role of wartime aggression. His 2013 visit to the Yasukuni shrine, which honors the nation’s war dead but is also where a number of convicted war criminals are memorialized, angered Seoul and Beijing.